Abstract

Wood fibers can be used to produce a wide variety of low-density, three-dimensional webs, mats, and fiber-molded products. Short wood fiber can be blended with a long fibers can be formed into flexible fiber mats, which can be made by physical entanglement, nonwoven needling or thermoplastic fiber melt matrix technologies. The three most common types of flexible mats are carded, air-laid, needle punched, and thermobonded mats. In carding, the fibers are combed, mixed and physically entangled into a felted mat. These are usually of high density but can be made at almost any density. Air-laid webs are made by laying down layers of wood fibers combined with a low melting thermoplastic fiber that is then passed through a heated chamber that melts the thermoplastic in the web. The heated web is then passed through calender rolls that press the melted fibers together with the wood fibers holding the web together. A needle punched mat is produced in a machine which passes a randomly formed machine made web through a needle board that produces a mat in which the fibers are mechanically entangled. The density of air-laid webs and needled mats can be controlled by the amount of fiber going through the processes or by overlapping webs or mats to give the desired density. A thermobonded mat is made by combining natural fibers with a thermoplastic fiber in the needled mat technology that is then melted in a heated press holding the mat together. The webs and mats can be used as filters, geotextiles, sorbents, and mulch mats.